Cardio-Oncology is the care of cancer
patients with cardiovascular disease, overt or occult, already established or
acquired during treatment.

The mortality rate among patients
with cancer has decreased dramatically over the last 20 to 30 years. However,
the toxicity of conventional cancer treatment (both chemotherapy and
radiotherapy) is greater than previously appreciated and is a leading cause of
morbidity and mortality in survivors.1 New “targeted therapies” are being
developed at a rapid pace many of which have recognised or unrecognised
cardiovascular toxicities.

Although Cardio-Oncology is often
regarded as synonymous with treating the cardiovascular toxicity of cancer
therapies, it is important to remember that there are other interactions
between cancer and heart disease with many common risk factors and disease
pathways at cell and molecular level.2 The cardiac toxicities of cancer
treatment include heart failure, cardiac ischaemia, arrhythmias, pericarditis,
valve disease and fibrosis of the pericardium and myocardium.3

While Cardio-Oncology services have
been established in the USA and in parts of Europe it is still a relatively new
concept in the UK and many other countries. Nevertheless, a perceived clinical
need is driving a number of hospitals to develop formal Cardio-Oncology
services. Cancer patients can present with a variety of cardiovascular problems
not all of which are directly related to cancer therapy (medications or
radiotherapy). Optimal individual care requires close collaboration between cardiology
and oncology specialists.

The authors have been involved in
establishing Cardio-Oncology services at the Barts Heart Centre, St
Bartholomew’s Hospital London and University College London Hospital and have
used their experiences to inform this review, exploring this new subspecialty
in the context of common cardiology problems encountered by cancer patients.

Arrhythmias and device issues – collaborating with the Electrophysiology
(EP) team

Arrhythmias are frequently associated
with treatment in cancer patients.4,5 The commonest unsurprisingly is atrial
fibrillation (AF),6,7 but supraventricular tachycardias
and repolarization issues, particularly QT prolongation and torsades de pointes
(TdP) are also encountered.8

Multiple studies have demonstrated an
increased association between AF and malignancies and chemotherapy, even accounting
for conventional AF risk factors.6 The mechanisms9 by which chemotherapeutic agents can
cause AF vary and are outside the scope of this article. However, the treatment
on AF in cancer patients is challenging as many rhythm-controlling agents
interact with cancer therapies and even though these patients may have an increased
propensity to stroke, anticoagulation can also be problematic, due to anaemia
and low platelet counts which are prevalent in this population. Ablation is of
course an option in these patients although here, as in most other areas of
Cardio-Oncology, there is a dearth of high-quality (i.e. Class 1 Level A)
evidence.10

Many cancer drugs prolong the QT
interval. In addition, a number of co-existing factors in cancer patients can
affect the QT interval (Figure 1). This can lead to potentially fatal TdP.